CN109990083B

CN109990083B - Acceleration control method for DCT vehicle

Info

Publication number: CN109990083B
Application number: CN201810834479.7A
Authority: CN
Inventors: 金镇成; 姜东协
Original assignee: Hyundai Motor Co; Kia Motors Corp
Current assignee: Hyundai Motor Co; Kia Corp
Priority date: 2018-01-02
Filing date: 2018-07-26
Publication date: 2021-12-14
Anticipated expiration: 2038-07-26
Also published as: US10556594B2; KR20190082608A; US20190202461A1; KR102476379B1; CN109990083A

Abstract

The invention relates to an acceleration control method of a DCT vehicle, which comprises the following steps: an acceleration condition determination step in which the controller determines whether or not the engine speed is less than a target gear input shaft speed when the acceleration request of the driver is confirmed; a speed reaching determination step in which the controller determines whether or not the engine speed is increased to a state equal to or higher than a target shift input shaft speed in response to the acceleration request from a state in which the engine speed is lower than the target shift input shaft speed; a synchronization step of performing feedback control of the engagement-side clutch in a direction to reduce slip, which is a difference between the engine speed and the target shift speed input shaft speed, while maintaining the engine torque, when it is confirmed in the speed arrival determination step that the engine speed is equal to or higher than the target shift speed input shaft speed; and an acceleration starting finishing step of finishing the control after confirming that the state of the engine speed and the speed of the target speed change gear input shaft is stable.

Description

Acceleration control method for DCT vehicle

Technical Field

The present invention relates to an acceleration control method of a vehicle equipped with a DCT (DUAL CLUTCH TRANSMISSION), and more particularly to a control technique of accelerating the vehicle from a state in which an engine speed is lower than a target shift stage input shaft speed.

Background

In a vehicle equipped with a DCT, two clutches are arranged to receive power from an engine and to provide the power to drive wheels after shifting gears, the two clutches are arranged to be connected to respective input shafts in the DCT so as to be able to realize gear stages arranged in the respective input shafts, the gear stages arranged in the two input shafts are generally divided into odd-numbered stages and even-numbered stages in a series of gear stages, and one of the input shafts is arranged to realize only the odd-numbered stages and the other input shaft is arranged to realize only the even-numbered stages.

Upshifting (upshifting) refers to shifting to an upper gear in a series of gears, and in the case of DCT, the upshifting is performed while traveling in a gear N gear that is disposed on one input shaft, and refers to shifting to an N +1 gear that is disposed on the other input shaft.

At this time, it is necessary to release the clutch connected to the input shaft that realizes the current speed change stage N stage and reduce the torque input from the engine, engage the clutch connected to the input shaft that realizes the target speed change stage N +1 stage and increase the torque input from the engine.

At the time of gear shifting, the clutch that is released while reducing the torque input from the engine as described above is referred to as a "release-side clutch", the input shaft connected thereto is referred to as a "release-side input shaft", the clutch that is engaged so as to increase the torque input from the engine is referred to as a "engagement-side clutch", and the input shaft connected thereto is referred to as a "engagement-side input shaft" or a "target gear input shaft".

In order to prevent a shock from occurring when the engine speed becomes higher than the target gear input shaft speed in the case where the engine speed at the acceleration start time is lower than the target gear input shaft speed in accordance with the acceleration request when the driver steps on the accelerator pedal again to display the intention to accelerate during deceleration while the vehicle is traveling, a control is performed to forcibly reduce the engine torque and then increase the engine torque together with the clutch torque on the engagement side.

The matters described above as background of the invention are only for enhancement of understanding of the background of the invention and should not be construed as admissions of prior art known to those skilled in the art.

Documents of the prior art

Patent document

(patent document 1) JP 5847514B 2

(patent document 2) KR 10-1371745B 1

(patent document 3) KR 10-1393882B 1

Disclosure of Invention

Technical problem to be solved by the invention

An object of the present invention is to provide an acceleration control method for a DCT-equipped vehicle, which can prevent acceleration delay to ensure rapid response performance and prevent occurrence of a shock to improve acceleration feeling of the vehicle, when acceleration is required in accordance with a driver's request from a state where an engine speed of the DCT-equipped vehicle is lower than a target gear input shaft speed.

Technical solution for solving technical problem

The acceleration control method of the DCT vehicle according to the present invention for achieving the above object is characterized by comprising the steps of:

an acceleration condition determination step of determining whether or not the engine speed is less than a target gear input shaft speed when the controller confirms a driver's acceleration request;

a speed reaching determination step in which the controller determines whether or not the engine speed is increased to a state equal to or higher than a target shift input shaft speed in response to the acceleration request from a state in which the engine speed is lower than the target shift input shaft speed;

a synchronization step of performing feedback control of the engagement-side clutch in a direction to reduce slip, which is a difference between the engine speed and the target shift speed input shaft speed, while maintaining the engine torque, when it is confirmed in the speed arrival determination step that the engine speed is equal to or higher than the target shift speed input shaft speed; and

and an acceleration starting finishing step of finishing the control after confirming that the state of the engine speed and the speed of the target speed change gear input shaft is stable.

In the acceleration condition determining step, the acceleration request of the driver may be confirmed by switching the accelerator sensor from the off state to the on state, and the engine speed at the time point when the accelerator sensor signal is in the on state may be compared with the target gear input shaft speed.

After the speed reaching determination step and before the synchronization step, a speed stability confirmation step may be further performed for confirming whether or not a state in which the engine speed is stably secured at or above the target shift speed input shaft speed is ensured.

In the above-mentioned speed stability confirmation step,

when the engine speed is higher than the target gear input shaft speed by a predetermined reference upper limit speed or more, it can be determined that the engine speed is stably maintained at the target gear input shaft speed or more.

In the above-mentioned speed stability confirmation step,

when the engine speed is maintained at or above a predetermined reference time between a predetermined upper limit speed and a predetermined lower limit speed, the engine speed being greater than or equal to the target gear input shaft speed, it can be determined that the engine speed is stably maintained at or above the target gear input shaft speed.

In the acceleration condition determining step, when the driver's acceleration request is confirmed in a state where the engine speed is lower than the target gear input shaft speed, the controller may gradually increase the coupling-side clutch torque until the synchronization step is started, based on a difference between the engine torque and the clutch torque and an accelerator pedal sensor signal.

When the engaging side clutch torque is gradually increased until the synchronization step is started, the engaging side clutch torque may be determined according to the following equation:

the engagement-side clutch torque (k) is defined as engagement-side clutch torque (k-1) + Δ torque (k),

Δ torque (k) ═ f (engine torque (k-1) — coupling-side clutch torque (k-1), APS signal).

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can prevent acceleration delay to ensure rapid response performance and prevent impact from being generated under the condition that the engine speed of a DCT-equipped vehicle is lower than the target gear input shaft speed and the acceleration is required according to the requirement of a driver, thereby improving the acceleration feeling of the vehicle.

Drawings

Fig. 1 is a configuration diagram of a DCT vehicle to which the control method of the present invention can be applied.

Fig. 2 is a flowchart illustrating an embodiment of an acceleration control method of a DCT vehicle according to the present invention.

Fig. 3 is a graph illustrating a control method according to the present invention.

Description of the reference numerals

E; engine

CL1, CL 2; clutch device

I1, I2; input shaft

W; driving wheel

CLR; controller

An ECU; engine control unit

CA; clutch actuator (clutch actuator)

GA; gear actuator (gear actuator)

An APS; accelerator pedal sensor

S10; acceleration state determination step

S20; clutch torque ramping step

S30; speed arrival judging step

S40; speed stability confirming step

S50; synchronization step

S60; finish step of acceleration starting

Detailed Description

Fig. 1 is a diagram illustrating a configuration of a DCT vehicle to which the present invention can be applied, and is configured such that power of an engine (E) is selectively supplied to two input shafts (I1, I2) through two clutches (CL1, CL2) of the DCT, and power after the DCT completes a gear shift is supplied to a driving wheel (W).

The Controller (CLR) is connected to an ECU (Engine Control Unit) so as to be able to receive information such as Engine torque and send a request such as torque reduction to the Engine (E), and is connected to Control a Clutch Actuator (CA) that controls the two clutches of the DCT and a Gear Actuator (GA) that changes the gear engagement state of the DCT.

The Controller (CLR) is configured to receive a signal of an Accelerator Pedal Sensor (APS), and is configured to be capable of receiving a rotational speed and the like of each input shaft (I1, I2) of the DCT.

The two clutches may be divided into a clutch that realizes the current gear at the time of gear shift and a clutch that realizes a new target gear, and hereinafter, a clutch that originally realizes the current gear and needs to be released as the gear shift progresses is referred to as a "release-side clutch", and a clutch that is gradually engaged to realize the target gear is referred to as a "engagement-side clutch".

In addition, according to the division of the clutches, the input shaft connected to the clutch on the release side is referred to as a clutch on the release side, and the input shaft connected to the clutch on the coupling side is referred to as a coupling side input shaft.

In the following description, the "target gear input shaft speed" refers to the rotational speed of the input shaft for achieving the target gear when the transmission gear of the target gear is engaged, and is the same as the coupling-side input shaft speed.

Referring to fig. 2, an embodiment of an acceleration control method of a DCT vehicle of the present invention includes the steps of: an acceleration condition determination step (S10) in which the Controller (CLR) determines whether or not the engine speed (Ne) is lower than a target gear input shaft speed (Ni) when the driver' S acceleration request is confirmed; a speed reaching determination step (S30) in which the controller determines whether or not the engine speed is increased to a state equal to or higher than a target shift speed input shaft speed in response to the acceleration request from a state in which the engine speed is lower than the target shift speed input shaft speed; a synchronization step (S50) in which, when it is confirmed in the speed arrival determination step (S30) that the engine speed is equal to or higher than the target shift input shaft speed, the controller performs feedback control for reducing the engagement-side clutch in a direction to reduce slip, which is the difference between the engine speed and the target shift input shaft speed, while maintaining the engine torque; and an acceleration start completion step (S60) for ending the control after confirming that the state of the engine speed and the target gear input shaft speed are synchronized is stable.

In the acceleration state determining step (S10), the driver' S acceleration request is confirmed by switching the accelerator sensor from the off state to the on state, and the engine speed at the time point when the accelerator sensor signal is in the on state is compared with the target gear input shaft speed to determine whether or not the engine speed is lower than the target gear input shaft speed.

In the acceleration condition determining step (S10), when the driver' S acceleration request is confirmed in a state where the engine speed is lower than the target gear input shaft speed, the controller executes a clutch torque increasing step (S20) of gradually increasing the engaging side clutch torque until the synchronization step (S50) is started, in accordance with a difference between the engine torque and the clutch torque and an accelerator pedal sensor signal.

In this case, the engagement side clutch torque may be determined by the following equation.

Δ Torque (k) ═ f (Engine Torque (k-1) — Clutch Torque on coupling side (k-1), APS Signal)

Where k is a control cycle index (control cycle index) of the controller, k indicates the current control cycle, and k-1 indicates the previous control cycle.

That is, the above-described engaging side clutch torque is controlled in a gradually rising manner, the rising amplitude thereof is adjusted according to the difference between the engine torque and the engaging side clutch torque of the previous control cycle and the accelerator pedal operation amount of the driver indicated by the APS signal, and is determined using a map prepared in advance through a plurality of experiments and analyses or a function relationship set so that the engaging side clutch torque is raised within a range that allows the engine speed to be raised as quickly as possible according to the driver's accelerator pedal operation without generating a shock.

Therefore, in the present invention, when the APS signal is turned on from the off state as in a situation where the vehicle is decelerating and the vehicle is requested to accelerate, if the engine speed is lower than the target shift input shaft speed, the control of not increasing the engagement-side clutch torque until the engine speed exceeds the target shift input shaft speed and then increasing the engine torque together with the engagement-side clutch torque by forcibly decreasing the engine torque as in the conventional art is not performed, but the engagement-side clutch torque is completely engaged by immediately starting the increase of the engagement-side clutch torque and maintaining the engine torque and decreasing the slip when the engine speed becomes equal to or higher than the target shift input shaft speed, whereby a larger engine torque is transmitted to the drive wheels in a shorter time to prevent the acceleration delay of the vehicle, ensuring rapid acceleration response performance.

In the present embodiment, after the speed arrival determination step (S30) and before the synchronization step (S50), a speed stability confirmation step (S40) is further performed for confirming whether or not a state in which the engine speed is equal to or higher than the target shift speed input shaft speed is stably ensured.

In the speed stability confirming step (S40), when the engine speed is higher than the target shift speed input shaft speed by a predetermined reference upper limit speed or more, it may be determined that the engine speed is stably maintained at the target shift speed input shaft speed or higher.

The reference upper limit speed is determined in advance by experiments and explanations according to the above purpose, and may be set to, for example, 50 RPM.

In the speed stability confirmation step (S40), it may be determined that the engine speed is stably maintained at the target gear input shaft speed or higher when the engine speed is maintained at the predetermined reference time or longer by the maintenance time between the larger predetermined reference upper limit speed and the smaller predetermined reference lower limit speed with respect to the target gear input shaft speed.

That is, even if the engine speed is not increased to the reference upper limit speed or more compared to the target gear input shaft speed, but is maintained without separation for the reference time or more within the speed range between the upper side to the reference upper limit speed and the lower side to the reference lower limit speed with respect to the target gear input shaft speed, it can be considered that the engine speed is stably increased, and therefore, in this case, it is also determined that the engine speed is stably increased to such an extent that the transition to the synchronization step (S50) is possible.

Therefore, the above-mentioned reference upper limit speed and reference lower limit speed may be determined as appropriate values by experiments and explanations according to the purpose as described above, and may be set to, for example, 50RPM, -50 RPM, etc., respectively.

For example, in the present embodiment, both examples of performing the above-described speed stability confirmation step (S40) are used.

In the above synchronization step (S50), the engine torque is maintained at the torque determined according to the APS, instead of forcibly reducing the engine torque as in the related art. The control of the engagement-side clutch torque so that the slip, which is the difference between the engine speed and the target gear input shaft speed, gradually decreases can be achieved by performing feedback control so that a target slip change rate is set in advance and the slip gradually decreases according to the change rate.

As shown in fig. 2, the acceleration start completion step (S60) is configured to: when the timing of repeating the control cycle and integrating the state where the engine speed and the target gear input shaft speed are synchronized exceeds a predetermined set value, it is determined that the synchronized state is stable, and the control of the present invention is ended.

Of course, the above-mentioned set value is preferably set to the following level as appropriate: the engagement-side clutch torque is sufficiently increased, and it can be determined that the engine speed and the target gear speed are reliably and stably maintained in synchronization.

It will be apparent to those skilled in the art that while the present invention has been shown and described with respect to certain embodiments thereof, various modifications and changes can be made without departing from the spirit of the invention as defined by the appended claims.

Claims

1. An acceleration control method of a dual clutch transmission vehicle, characterized by comprising the steps of:

an acceleration condition determination step in which the controller determines whether or not the engine speed is less than a target gear input shaft speed when the acceleration request of the driver is confirmed;

a speed reaching determination step in which the controller determines whether or not the engine speed is increased to a state equal to or higher than a target shift input shaft speed in accordance with the acceleration request from a state in which the engine speed is lower than the target shift input shaft speed;

a synchronization step of, when it is confirmed in the speed reaching determination step that the engine speed is equal to or higher than the target shift input shaft speed, feedback-controlling the engagement-side clutch in a direction to reduce slip, which is a difference between the engine speed and the target shift input shaft speed, while maintaining the engine torque;

and an acceleration starting completion step of finishing the control after confirming a state that the engine speed is synchronous with the speed of the target speed change gear input shaft.

2. The acceleration control method of a dual clutch transmission vehicle as set forth in claim 1, characterized in that:

in the acceleration condition determining step, the acceleration request of the driver is confirmed by switching the accelerator sensor from the off state to the on state, and the engine speed at the time point when the accelerator sensor signal is in the on state is compared with the target gear input shaft speed.

3. The acceleration control method of a dual clutch transmission vehicle as set forth in claim 1, characterized in that:

after the speed arrival determination step and before the synchronization step, a speed stability confirmation step is further performed for confirming whether or not a state in which the engine speed is stably secured at or above the target shift speed input shaft speed is ensured.

4. A method of acceleration control of a dual clutch transmission vehicle as set forth in claim 3 wherein:

in the speed stability confirmation step, the speed stability determination step,

when the engine speed is greater than the target gear input shaft speed by a predetermined reference upper limit speed or more, it is determined that a state in which the engine speed is equal to or greater than the target gear input shaft speed is stably secured.

5. A method of acceleration control of a dual clutch transmission vehicle as set forth in claim 3 wherein:

and determining that the engine speed is stably maintained at the target gear input shaft speed or higher when the engine speed is maintained at or above a predetermined reference time: a holding time between a predetermined reference upper limit speed greater than the target shift speed input shaft speed and a predetermined reference lower limit speed lower than the target shift speed input shaft speed.

6. The acceleration control method of a dual clutch transmission vehicle as set forth in claim 1, characterized in that:

in the acceleration condition determining step, when a driver's acceleration request is confirmed in a state where the engine speed is lower than the target gear input shaft speed, the controller gradually increases the coupling-side clutch torque until the synchronization step is started, based on a difference between the engine torque and the clutch torque and an accelerator pedal sensor signal.

7. An acceleration control method of a double clutch transmission vehicle as set forth in claim 6, characterized in that:

when gradually increasing the engaging-side clutch torque until before the synchronization step starts, the engaging-side clutch torque is determined according to the following mathematical formula:

Δ torque (k) ═ f (engine torque (k-1) — coupling-side clutch torque (k-1), APS signal),

wherein k represents the current control cycle, k-1 represents the previous control cycle, and f is a preset function.